1. Field of the Invention
The invention relates generally to cyanate esters and thermosets made therefrom.
2. Description of the Prior Art
Cyanate ester (CE) resins have received considerable attention due to their importance as a thermosetting resin for use in the electronics, aerospace, and adhesive industries. Cyanate ester resins have found extensive use in applications where low-dielectric and high thermal stability materials are needed. Such applications include printed circuit boards and radomes. More recently, CE resins have been proposed for use as the matrix in structural composites for aircrafts. In aerospace applications, it may be desirable for the matrix material to show high temperature stability, low flammability, high strength, and toughness.
CEs can have the processability of epoxies with the heat and fire resistance of phenolic resins. They can have their own unique properties such as good strength, low dielectric constants, radar transparency, low water absorption, and superior metal adhesion. These properties can make them useful for high performance applications. Current CE resins have the required flammability but are too brittle for use alone as matrix materials for structural applications.
To enhance the toughness, modifiers such as thermoplastics and elastomers have been blended with the CE resins, which have had a negative impact on the flammability. A variety of CE monomers have been synthesized containing polystyrene, substituted phenols and allyl-functionalized moieties. These CE monomers cure alone or by the aid of a catalytic amount of a metal salt into a triazine network.